Do tires dry rot? what does a dry rotted tire look like?

A six year old tire that is used daily, will that tire dry rot?

Is there a greater possibilty of a non-mounted tire dry rotting as opposed to a mounted tire?

Tires, rubber and vinyl care by Larry Reynolds at CarCareOnline.com

There are two main degrading agents that attack tires and rubber trim. They are UV light waves and ozone. Both of these attack the long hydrocarbon chains of the rubber and by breaking these bonds, shorten the molecules with resulting loss of elasticity and other problems. Tire manufacturers add two primary sacrificial protectants to the rubber. To protect against UV, they add carbon black. This is why tires don't come in designer colors to match your paint. The carbon black will turn white/gray as it absorbs the UV and dissipates the energy as heat. Thus the basis of rubber parts turning gray as they age. To protect against ozone, tire manufacturers add a wax based sacrificial protectant. The ozone attacks the wax and depletes it. As the tire rolls, additional wax is forced to the surface of the tire. This is referred to as "blooming". This blooming refreshes the surface wax protectant. A tire that has not been flexed will have the wax depleted by the ozone and thus begin to degrade and suffer "dry rot". The raw silicone oil that is the main ingredient in most of the nationally advertised over the counter products may actually dissolve the wax and be the cause of premature tire sidewall cracking/failure. The quality tire/rubber dressings should contain a strong UV protectant to bolster the efforts of the carbon black and not contain any raw silicone oil. Many of the nationally advertised rubber and vinyl products also contain formaldehyde. If you plan on having a funeral for your dash, then you may wish to use one of these products.

My personal favorite tire and exterior rubber/vinyl trim protectant is Black Again. It is, in my opinion, the best non-silicone oil based product to restore the jet-black patina to tires and exterior rubber/vinyl. A white creamy polymer emulsion, with a heavy duty UV protectant, it works equally well on all colors of exterior trim. (They tried calling it Any Color Again, but the name didn't work). If raw silicone oil based products have been previously applied to the rubber/vinyl, the raw silicone oil had saturated the material. Black Again will help dissolve out the silicone oil (this is good), but does not seem to be able to do so evenly (this is bad). The finish may be slightly "splotchy" the first couple of applications of Black Again. The only solution is to apply several coats about a week apart, and the finish will eventually even out. An excellent spray on type of protectant for tires and rubber trim is One Grand Exterior Rubber Treatment. Spray on, allow to penetrate and buff off the excess, leaving a medium gloss, non-greasy finish. Harly Tire Nu is another spay on product with a high gloss finish. Meguiar #40 is a vinyl and rubber cleaner and conditioner. I feel it works better on vinyl than it does on rubber. Leaves a medium gloss finish. Sonax Trim Protectant cleans and protects exterior vinyl and rubber, producing a high gloss finish. Zymol Tyre is a new product that leaves a medium gloss and helps restore some of the black patina to rubber. Wurth Rubber Care, Sonax Rubber Care and Zymol Seal are designed for the "live" rubber door gaskets. These products are rich in glycerin and help maintain the flexibility and sealing ability of the gaskets. A nice side benefit is that they help keep doors from freezing in winter.

If you have any questions or if you need any further information, please feel free to contact us.

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If a tire has lots of small cracks making squares or rectangles on the surface of the sidewall, suspect it. Eventually the rubber will separate from the steel belts, and you will have all the fun of blistered, out of balance, one-side-larger-than-the-other tires.

Rubber also tends to get harder as it ages, so you have less traction even if the tread is still good.

Six years old and sitting in one spot most of the time, the tires also won't be particularly round anymore, so you will get vibration.

Plan on new ones soon.

Peter

__________________
1972 220D ?? miles
1988 300E 200,012
1987 300D Turbo killed 9/25/07, 275,000 miles
1985 Volvo 740 GLE Turobodiesel 218,000
1972 280 SE 4.5 165, 000 - It runs!

What about a set of tires (mounted) but not on the vehicle, sitting flat on top of each other and covered from UV? Is there a better way of storing them long term?

Thank you in advance.

Sorry Ethan, don't mean to hijack your thread.

That's about as good as you can do, as far as I know. Protection from UV and ozone will go a long way.

However, the oxygen in the air will still age them somewhat. I don't plan on using the spare tire in the 220D for any real driving -- it was made in Austria, I suspect an original tire. Looks fine, but I'd bet it will shed the tread in an hour on the highway.....

Peter

__________________
1972 220D ?? miles
1988 300E 200,012
1987 300D Turbo killed 9/25/07, 275,000 miles
1985 Volvo 740 GLE Turobodiesel 218,000
1972 280 SE 4.5 165, 000 - It runs!

I still have the original spare sitting in the boot.

Any recommendations to changing an unused spare? The thought of it falling to bits in the middle of nowhere is not good.

However, the tire shop guys always give me this "don't be stupid" look whenever I suggest a change of the spare...........

__________________
1983 w126 280SE - daily drive
1983 w123 200 - sold

I recently inherited my father's '91 Ford F-150 with only 23,500 miles on it (in the three months since we have added 5,000 more) and the original General light truck tires (235/75X15). This vehicle sat in a closed farm machine shed in a cold climate almost all the time, and the tires look and feel like new. I have had occasion to use hard braking since then, and could not complain about the amount of traction, given the type of tires they were to begin with. I shall, of course, keep a close watch on them, as I always do on my vehicles' tires, but I have no anxieties at all about their ability to retain their structural integrity until the tread wears out. Some of the tires, though, on other farm machinery out there at home (23 miles NE of the mythical site of Lake Wobegon) are nearly 30 years old, and they do look a little cracked up and feel like stiff cardboard.

Finum:

The spare in the 220D, if original, is 31 years old..... I don't relish the idea of actually using it, sitting in the dark all this time or not.

Say hi to my nephew, he just started at William and Mary this fall!

Peter

__________________
1972 220D ?? miles
1988 300E 200,012
1987 300D Turbo killed 9/25/07, 275,000 miles
1985 Volvo 740 GLE Turobodiesel 218,000
1972 280 SE 4.5 165, 000 - It runs!